200
G. L. CANTONI
whereas ercinine has been found in certain fungi (83, 84). Cysteine is
the most effective precursor of the sulfur atom of ergothioneine. When
fed to Neurospora, cysteine competes very effectively with inorganic
sulfate and in this regard is more effective than methionine, choline
sulfate, or thioacetamide. Direct evidence of the utilization of cysteine
sulfur for the biosynthesis of ergothioneine was supplied by the finding
that when S
35 -cysteine was used, the sulfhydryl group of ergothioneine
was labeled with S
35 . It has been shown that the methyl groups in
ergothioneine are derived from methionine through a transmethylation
reaction. This has not been demonstrated directly in a cell-free system
but it may be inferred from the data of Melville et al. (79) who have
shown in feeding experiments using methionine labeled with both C
14
and deuterium in the methyl group that the methyl group is transferred
as a unit. Using Claoiceps purpurea Heath and Wildy (80-82) independently have obtained results which are in close agreement with this
general pattern. It is thus well established that fungi are able to synthesize ergothioneine and it is quite possible that they are uniquely
endowed in this respect.
It is of interest to point out that in cultures of C. purpurea grown
on chemically defined media the formation of ergothioneine was confined to the conidia and it was found moreover that formation of
sclerotia was not necessary for the production of the betaine. This fact,
together with reported occurrence of ergothioneine in seeds and in
semen suggested to Heath and Wildy the possibility that one of the
biological functions of ergothioneine might be in some way related to
germination. Although preliminary attempts to document this hypothesis
by examining the effect of ergothioneine on the growth rate of cress
seed were negative, this interesting idea seems to deserve further study.
In the course of their work, Heath and Wildy made an incidental
observation which is of interest in connection with the over-all problem of alkaloid biosynthesis. Namely they observed that the characteristics of the culture C. purpurea changed during the course of the experiment with an increase in the ability to form ergothioneine taking
place concomitantly with an increase in the pigmentation of the conidia.
Although the fact that ergothioneine is not synthesized in the mammal but is of dietary origin is now well established, it is becoming clear
that there are other factors which govern the occurrence and distribution of ergothioneine in mammals. Thus, the distribution of ergothioneine in the accessory sexual secretions of the male does not fall into a
clear pattern: its presence is not confined to boar semen as it has been
found in the stallion, in the mole, and in the hedgehog but it is absent
from the semen of man, bull, and ram. As for red blood cells, the Mac-
G. L. CANTONI
whereas ercinine has been found in certain fungi (83, 84). Cysteine is
the most effective precursor of the sulfur atom of ergothioneine. When
fed to Neurospora, cysteine competes very effectively with inorganic
sulfate and in this regard is more effective than methionine, choline
sulfate, or thioacetamide. Direct evidence of the utilization of cysteine
sulfur for the biosynthesis of ergothioneine was supplied by the finding
that when S
35 -cysteine was used, the sulfhydryl group of ergothioneine
was labeled with S
35 . It has been shown that the methyl groups in
ergothioneine are derived from methionine through a transmethylation
reaction. This has not been demonstrated directly in a cell-free system
but it may be inferred from the data of Melville et al. (79) who have
shown in feeding experiments using methionine labeled with both C
14
and deuterium in the methyl group that the methyl group is transferred
as a unit. Using Claoiceps purpurea Heath and Wildy (80-82) independently have obtained results which are in close agreement with this
general pattern. It is thus well established that fungi are able to synthesize ergothioneine and it is quite possible that they are uniquely
endowed in this respect.
It is of interest to point out that in cultures of C. purpurea grown
on chemically defined media the formation of ergothioneine was confined to the conidia and it was found moreover that formation of
sclerotia was not necessary for the production of the betaine. This fact,
together with reported occurrence of ergothioneine in seeds and in
semen suggested to Heath and Wildy the possibility that one of the
biological functions of ergothioneine might be in some way related to
germination. Although preliminary attempts to document this hypothesis
by examining the effect of ergothioneine on the growth rate of cress
seed were negative, this interesting idea seems to deserve further study.
In the course of their work, Heath and Wildy made an incidental
observation which is of interest in connection with the over-all problem of alkaloid biosynthesis. Namely they observed that the characteristics of the culture C. purpurea changed during the course of the experiment with an increase in the ability to form ergothioneine taking
place concomitantly with an increase in the pigmentation of the conidia.
Although the fact that ergothioneine is not synthesized in the mammal but is of dietary origin is now well established, it is becoming clear
that there are other factors which govern the occurrence and distribution of ergothioneine in mammals. Thus, the distribution of ergothioneine in the accessory sexual secretions of the male does not fall into a
clear pattern: its presence is not confined to boar semen as it has been
found in the stallion, in the mole, and in the hedgehog but it is absent
from the semen of man, bull, and ram. As for red blood cells, the Mac-